Integrated circuits (ICs) are typical formed in protective packages for handling and assembly onto printed circuit boards and to protect the devices from damage. A very large number of different types of package exist. IC packages that contain devices designed to handle significant power levels, e.g., power MOSFET devices, may be referred to as high-power IC packages or simply power IC packages.
In typical power IC packages, e.g., MOSFET devices, in order to improve device performance, high current may need to be applied to the device to help lower the RDS(on) (Drain-Source on resistance). One technique to address this is to apply multiple wire bonds to connect the source to the package lead frame. However, the wire resistance and contact resistances limit the effectiveness of such design. Another technique is solder attach a discrete copper clip onto the package lead frame to connect it to the MOSFET Source terminal. However, this solution adds cost.
Another common technique is to solder attach a discrete copper clip to the source pad of the die and solder the other end to the package lead frame pad. FIG. 1 shows an example structure formed according to this conventional technique. In particular, FIG. 1 is a top view of an example conventional MOSFET DFN (dual-flat no-leads) MOSFET package 10 during fabrication. Package 10 includes a lead frame 12 including a die-attach pad (DAP) 14 and a plurality of lead fingers 16 extending from the DAP 14. A MOSFET die 20 is mounted to the DAP 14, e.g., by epoxy, and secured using a copper clip 30, which may be solder attached to the lead frame 12. However, the copper clip 30 and the associated assembly steps typically add significant cost to the package, and may require an investment in custom automated assembly equipment.
Another common issue in power IC packages is thermal management, e.g., due to the high operational currents. In the conventional techniques discussed above, the power device (e.g., power MOSFET) is typically solder attached onto the die-attach paddle (DAP) of the package lead frame. The heat dissipation capacity through the DAP is typically limited by the material properties and thickness of the lead frame.